NEET &#8211; CHEMISTRY SOLUTIONS MODEL &#8211; 2024

SOLUTIONS

1. An ideal solution is formed when its components
(a) have no volume change on mixing
(b) have no enthalpy change on mixing
(c) have both the above characteristics
(d) have high solubility

2. All form ideal solution except
(a) C6H6 and C6H5 CH3
(b) C2H6 and C2H5I
(c) C6H5Cl and C6H5 Br
(d) C2H5 Iand C2H5 OH

3. The relative lowering of the vapour pressure is equal to the ratio between the number of
(a) solute molecules to the solvent molecules
(b) solute molecules to the total molecules in the solution
(c) solvent molecules to the total molecules in the solution
(d) solvent molecules to the total number of ions of the solute.

4. Which of the following aqueous solution has minimum freezing point?
(a) 0.01 m NaCl
(b) 0.005 m C2H5OH
(c) 0.005 m MgI2
(d) 0.005 m MgSO4

5. Blood cells retain their normal shape in solution which are
(a) hypotonic to blood
(b) isotonic to blood
(c) hypertonic to blood
(d) equinormal to blood.

6. Which of the following modes of expressing concentration is independent of temperature?
(a) Molarity
(b) Molality
(c) Formality
(d) Normality

7. Which one is a colligative property?
(a) boiling point
(b) vapour pressure
(c) osmotic pressure
(d) freezing point

8. If 0.1 Msolution of glucose and 0.1 Msolution of urea are placed on two sides of the semipermeable membrane to equal heights,
then it will be correct to say that
(a) There will be no net movement across the membrane
(b) Glucose will flow towards urea solution
(c) urea will flow towards glucose solution
(d) water will flow from urea solution to glucose

9. At 25°C, the highest osmotic pressure is exhibited by 0.1 Msolution of
(a) CaCl2
(b) KCl
(c) Glucose
(d) Urea.

10. Which one of the following salts will have the same value of van’t Hoff factor as that of K4 [Fe (CN) 6].
(a) Al2 (SO4) 3
(b) NaCl
(c) Al (NO3) 3
(d) Na2 SO4

11. The number of moles of oxygen in one litre of air containing 21% oxygen by volume, in standard conditions, is
(a) 0.186
(b) 0.21
(c) 0.0093
(d) 2.10

12. Vapour pressure of benzene at 30°C is 121.8 mm. When 15 g of a non volatile solute is dissolved in 250 g of benzene its vapour pressure decreased to 120.2 mm. The molecular weight of the solute (Mo. wt. of solvent = 78)
(a) 356.2
(b) 456.8
(c) 530.1
(d) 656.7

13. According to Raoult’s law, relative lowering of vapour pressure for a solution is equal to
(a) moles of solute
(b) moles of solvent
(c) mole fraction of solute
(d) mole fraction of solvent

14. The vapour pressure at a given temperature of an ideal solution containing 0.2 mol of a nonvolatile solute and 0.8 mol of solvent is 60 mm of Hg. The vapour pressure of the pure solvent at the same temperature is
(a) 150 mm of Hg
(b) 60 mm of Hg
(c) 75 mm of Hg
(d) 120 mm of Hg

15. Which of the following 0.10 m aqueous solutions will have the lowest freezing point?
(a) Al2 (SO4) 3
(b) C6H12O6
(c) KCl
(d) C12H22O11

16. A 5% solution of cane sugar (mol. wt. =342) is isotonic with 1% solution of a substance X. The molecular weight of X is
(a) 34.2
(b) 171.2
(c) 68.4
(d) 136.8

17. The vapour pressure of a solvent decreased by 10mm of mercury when a non-volatile solute was added to the solvent. The mole fraction of
the solute in the solution is 0.2. What should be the mole fraction of the solvent if the decrease in the vapour pressure is to be 20mm of mercury?
(a) 0.8
(b) 0.6
(c) 0.4
(d) 0.2

18. Which of the following statements, regarding the mole fraction of a component in solution, is incorrect?
(a) 0 ≤ x ≤ 1

(b) x ≤ 1
(c) x is always non – negative
(d) -2 ≤ x ≤ 2

19. Which of the following colligative property can provide molar mass of proteins (or polymers or colloids) with greatest precision?
(a) Osmotic pressure
(b) Elevation of boiling point
(c) Depression of freezing point
(d) Relative lowering of vapour pressure

20. The beans are cooked earlier in pressure cooker, because
(a) Boiling point increases with increasing pressure
(b) Boiling point decreases with increasing pressure
(c) Internal energy is not lost while cooking in pressure cooker
(d) Extra pressure of pressure cooker, softens the beans

21. Molarity of liquid HCl will be, if density of solution is 1.17 gm/cc
(a) 36.5
(b) 32.05
(c) 18.25
(d) 42.10

22. 1 M, 2.5 litre NaOHsolution is mixed with another 0.5 M, 3 litre NaOH solution. Then find out the molarity of resultant solution
(a) 0.80 M
(b) 1.0 M
(c) 0.73 M
(d) 0.50 M

23. A solution contains non-volatile solute of molecular mass M2. Which of the following can be used to calculate the molecular mass of solute
in terms of osmotic pressure?

24. Asolution containing components Aand BfollowsRaoult’s law when
(a) A– B attraction force is greater than A– A and B– B
(b) A– B attraction force is less than A– A and B– B
(c) A– B attraction force remains same as A–A and B–B
(d) Volume of solution is different from sum of volume of solute and solvent

25. Camphor is often used in molecular mass determination because
(a) it is readily available
(b) it has a very high cryoscopic constant
(c) it is volatile
(d) it is solvent for organic substances

26. The vapour pressure of two liquids ‘P’ and ‘Q’ are 80 and 60 torr, respectively. The total vapour pressure of solution obtained by mixing 3 mole of Pand 2 mole of Qwould be
(a) 72 torr
(b) 140 torr
(c) 68 torr
(d) 20 torr

28. A solution of urea (mol. mass 56 g mol^-1) boils at 100.18° C at the atmospheric pressure. If Kfand Kb for water are 1.86 and 0.512 K kg mol-1 respectively, the above solution will freeze at
(a) 0.654°C
(b) – 0.654°C
(c) 6.54°C
(d) – 6.54°C

29. The mole fraction of the solute in one molal aqueous solution is:
(a) 0.009
(b) 0.018
(c) 0.027
(d) 0.036

30. A solution of acetone in ethanol
(a) shows a positive deviation from Raoult’s law
(b) behaves like a non ideal solution
(c) obeys Raoult’s law
(d) shows a negative deviation from Raoult’s law

31. During osmosis, flow of water through a semipermeable membrane is
(a) from both sides of semipermeable membrane with equal flow rates
(b) from both sides of semipermeable membrane with unequal flow rates
(c) from solution having lower concentration only
(d) from solution having higher concentration only

32. A solution containing 10 g per dm³ of urea (molecular mass = 60 g mol^-1 ) is isotonic with a 5% solution of a non-volatile solute. The
molecular mass of this non volatile solute is
(a) 300 g mol^-1
(b) 350 g mol^-1
(c) 200 g mol^-1
(d) 250 g mol^-1

33. 1.00 g of a non-electrolyte solute (molar mass 250 g mol^-1) was dissolved in 51.2 g of benzene. If the freezing point depression constant, Kfof benzene is 5.12 K kg mol^-1, the freezing point of benzene will be lowered by
(a) 0.3 K
(b) 0.5 K
(c) 0.4 K
(d) 0.2

34. 0.5 molal aqueous solution of a weak acid (HX) is 20% ionised. If Kffor water is 1.86 K kg mol^-1,the lowering in freezing point of the solution is
(a) 0.56 K
(b) 1.12 K
(c) – 0.56 K
(d) – 1.12 K

35. A0.0020 m aqueous solution of an ionic compound Co(NH3) 5 (NO2 ) Cl freezes at – 0.00732 °C. Number of moles of ions which 1 mol of ionic compound produces on being dissolved in water will be (Kf= – 1.86°C/m)
(a) 3
(b) 4
(c) 1
(d) 2

36. An aqueous solution is 1.00 molal in KI. Which change will cause the vapour pressure of the solution to increase?
(a) Addition of NaCI
(b) Addition of Na2 SO4
(c) Addition of 1.00 molal KI
(d) Addition of water

37. A solution of sucrose (molar mass = 342 g mol^-1) has been prepared by dissolving 68.5 g of sucrose in 1000 g of water. The freezing point of
the solution obtained will be (f for water = 1.86 Kkg mol^-1) .
(a) – 0.372°C
(b) – 0.520°C
(c) + 0.372°C
(d) – 0.570°C

38. 25.3 g of sodium carbonate, Na2 CO3 is dissolved in enough water to make 250 mLof solution. If sodium carbonate dissociates completely, molar concentration of sodium ions, Na⁺and carbonate ions, CO32- are respectively (Molar mass of Na2CO3 = 106 g mol^-1)
(a) 0.955 Mand 1.910 M
(b) 1.910 Mand 0.955 M
(c) 1.90 Mand 1.910 M
(d) 0.477 Mand 0.477 M

39. The freezing point depression constant for water is – 1.86ºCm^-1. If 5.00 g Na2 SO4 is dissolved in 45.0 g H2O, the freezing point is changed by – 3.82ºC. Calculate the van’t Hoff factor for Na2 SO4.
(a) 2.05
(b) 2.63
(c) 3.11
(d) 0.381

40. The van’t Hoff factor i for a compound which undergoes dissociation in one solvent and association in other solvent is respectively:
(a) less than one and greater than one.
(b) less than one and less than one.
(c) greater than one and less than one.
(d) greater than one and greater than one.

41. Mole fraction of the solute in a 1.00 molal aqueous solution is:
(a) 0.1770
(b) 0.0177
(c) 0.0344
(d) 1.7700

42. A 0.1 molal aqueous solution of a weak acid is 30% ionized. If Kffor water is 1.86°C/m, the freezing point of the solution will be
(a) – 0.18°C
(b) – 0.54°C
(c) – 0.36°C
(d) – 0.24°C

43. 200 mL of an aqueous solution of a protein contains its 1.26 g. The osmotic pressure of this solution at 300 Kis found to be 2.57 × 10^-3bar.
The molar mass of protein will be (R= 0.083 Lbar mol^-1K^-1)
(a) 51022 g mol^-1
(b) 122044 g mol^-1
(c) 31011 g mol^-1
(d) 61038 g mol^-1

44. PA and PB are the vapour pressure of pure liquid components, Aand B, respectively of an ideal binary solution. If XA represents the mole
fraction of component A, the total pressure of the solution will be.
(a) PA+ XA(PB– PA)
(b) PA+ XA(PA– PB)
(c) PB+ XA(PB– PA)
(d) PB+ XA(PA– PB)

45. Vapour pressure of chloroform (CHCl3) and dichloromethane (CH2Cl2) at 25ºC are 200 mm Hg and 41.5 mm Hg respectively. Vapour
pressure of the solution obtained by mixing 25.5 g of CHCl3 and 40 g of CH2Cl2 at the same temperature will be: (Molecular mass of CHCl3 =
119.5 u and molecular mass of CH2Cl2 = 85 u) .
(a) 173.9 mm Hg
(b) 615.0 mm Hg
(c) 347.9 mm Hg
(d) 285.5 mm Hg

46. How many grams of concentrated nitric acid solution should be used to prepare 250 mLof 2.0M HNO3? The concentrated acid is 70% HNO3
(a) 90.0 g conc. HNO3
(b) 70.0 g conc. HNO3
(c) 54.0 g conc. HNO3
(d) 45.0 g conc. HNO3

47. Which condition is not satisfied by an ideal solution?
(a) D_max H = 0
(b) D_max V =0
(c) D_max S = 0
(d)Obeyance to Roult’s law

48. Which of the following pair of solution having same physical state of solvent ?

(a) homogenous mixture of chloroform in N₂ gas, solution of CO₂ in water

(b) brass, solution of salt in water

(d) homogenous mixture of camphor in N₂ gas, moist air

49. Which one of the following is incorrect for ideal solution?

(a) ΔH_mix = 0

(b) ΔU_mix = 0

(d) ΔG_mix = 0

50. Which one of the statements given below concerning properties of solutions, describes a colligative effect?

(a) Boiling point of pure water decreases by the addition of ethanol

(b) Vapour pressure of pure benzene decreases by the addition of naphthalene

(d) Boiling point of pure benzene increases by the addition of toluene

51. What is the mole fraction of the solute in a 1.00 m aqueous solution?

(a) 1.710

(b) 0.177

(d) 0.0177

52. The vapour pressure of pure benzene at a certain temperature is 0.850 bar. A non-volatile, nonelectrolyte solid weighing 0.5 g is added to 39.0 g of benzene (molar mass 78 g/mol). The vapour pressure of the solution then is 0.845 bar. What is the molecular mass of the solid substance?

(a) 170

(b) 58

(d) 145

53. Which one of the following electrolytes has the same value of van’t Hoff factor (i) as that of Al₂(SO₄)₃ (if all are 100% ionised) ?

(a) Al(NO₃)₃

(b) K₄[Fe(CN)₆]

(d) K₃[Fe(CN)₆]

54. Which of the following unit of concentration does not depend on temperature ?

(a) formality

(d) normality

(d) molality

55. Of the following 0.10 m aqueous solutions, which one will exhibit the largest freezing point depression?

(a) KCI

(b) Al₂(SO₄)₃

(d) K₂SO₄

56. At 300K, the vapour pressure of an ideal solution containing 3 mole of A and 2 mole of B is 600 torr. At the same temperature, if 1.5 mole of A and 0.5 mole of C (non-volatile) are added to this solution the vapour pressure of solution increases by 30 torr. What is the value of 0 pB ?

(a) 90

(b) 940

(d) None of these

57. Which of the following possesses physical state of solute and solvent are liquid and solid respectively ?

(a) solution of sugar in water

(b) zinc amalgam

(d) brass

58. The vapour pressure of a solvent decreases by 10 mm of Hg when a non-volatile solute was added to the solvent. The mole fraction of the solute in the solution is 0.2. What should be the mole fraction of the solvent if the decrease in the vapour pressure is to be 20 mm of Hg ?

(a) 0.4

(b) 0.2

(d) 0.6

59. What amount of water is added in an aqueous solution of 5000 ml having concentration 1.5 M to prepare 0.5 M solution ?

(a) 10 litre

(d) 20 litre

(d) 5 litre

60. The van’t Hoff factor i for a compound which undergoes dissociation in one solvent and association in other solvent is respectively

(a) less than one and greater than one

(b) less than one and less than one

(d) greater than one and greater than one.

61. 200 mL of an aqueous solution of a protein contains its 1.26 g. The osmotic pressure of this solution at 300 K is found to be 2.57 x 10^-3 bar. The molar mass of protein will be (R = 0.083 L bar mol^-1K^-1)

(a) 51022 g mol^-1

(b) 61038 g mol^-1

(d) 31011 g mol^-1

62. A 0.0020 m aqueous solution of an ionic compound [Co(NH₃)₅(NO₂)]Cl freezes at – 0.00732°C. Number of moles of ions which 1 mol of ionic compound produces on being dissolved in water will be (Kf = 1.86°C/m)

(a) 3

(b) 4

(d) 2

63. Concentrated aqueous sulphuric acid is 98% H₂SO₄ by mass and has a density of 1.80 g mol-1. Volume of acid required to make one litre of 0.1 M H₂SO₄ solution is

(a) 16.65 mL

(b) 11.10 mL

(d) 5.55 mL

64. A solution of acetone in ethanol

(a) obeys Raoult’s law

(b) shows a negative deviation from Raclult’s law

(d) behaves like a near ideal solution

65. The vapour pressure of two liquids P and Q are 80 and 60 torr, respectively. The total vapour pressure of solution obtained by mixing 3 mole of P and 2 mol of Q would be

(a) 72 torr

(b) 20 torr

(d) 68 torr

66. A solution of urea (mol. mass 56 g mol-1) boils at 100.18°C at the atmospheric pressure. If Kf and Kb for water are 1.86 and 0.512 K kg mol-1 respectively, the above solution will freeze at

(a) 0.654°C

(b) – 6.54°C

(d) 6.54°C

67. Pure water can be obtained from sea water by

(a) centrifugation

(b) sedimentation

(d) reverse osmosis

Solutions :

1.Ans: (c) For ideal solution, DV_mixing= 0 and DH_mixing= 0

2.Ans: (d) C₂H₅I and C₂H₅OH form non ideal solution.

3.Ans: (b) According to Raoult’s law, the relative lowering in vapour pressure of a dilute solution si equal to the mole fraction of the solute present in the solution. = mole fraction of solute =

4.Ans: (a) DT_f =i ´ K_f ´ m Van’t Hoff factor , i = 2 for NaCl, Hence DT_f = 0.02 K_f which is maximum in the present case. Hence DT_f is maximum or freezing point is minimum.

5.Ans: (b)Blood cells neither swell or shrink in isotonic solution. AS isotonic solution have equal concentration therefore there is no flow of solvent is found and hence solvent neither enters nor flows out of the blood cells.

6.Ans: (b)The molality involves weight of the solute and solvent. Since weight does not change

7.Ans: (c)Osmotic pressure is a colligative property.

8.Ans: (a)As both solution are isotonic hence there is no net movement of the solvent through the semipermeable membrane between two solutions.

9.Ans: (a) Conc. of particles in CaCl₂ will be max as i= 3 max.Note : Glucose and Urea do not dissociate into ions, as they are nonelectrolytes.

10.Ans: (a) K₄ [Fe(CN)₆] and Al₂(SO₄)₃ both dissociates to give 5 ion or I = 5

K₄[Fe(CN)₆ 4K⁺ +[Fe(CN)₆]^–

Al₂(SO₄)₃ ⇌ 2Al³⁺ + 3SO₄^—

19.Ans: (a)molecular masses of polymers are best determined by osmotic pressure method. Firstly because other colligative properties give so low values that they cannot be measured accurately , secondly , osmotic pressure measurement can be made at room temperature , and do not require heating which may change the nature of the polymer.

20.Ans: (a)The beans are cooked earlier in pressure coockerbecause boiling point increases with increasing pressure.

24.Ans: (c)These two components A and B follows the condition of Raoult’s law if the force of attraction between A and B is equal to the force of attraction between A and A or B and B.

25.Ans: (b)Solvent having high cryoscopic constant can be used in determination of molecular mass by cryoscopic method.

Thus the freezing point of solution will be – 0.654^oC.

30.Ans: (a)A solution of acetone in ethanol shows positive deviation from Raoult’s law. It is because ethanol molecules are strongly hydrogen bonded. When acetone is added , these molecules break the hydrogen bonds and ethanol becomes more volatile. Therefore its vapour pressure is increased.
31.Ans: (c)During osmosis water flows through semiperable membrane from lower concentration to heigher concentration.

= 1.12K

36.Ans: (d) When the aqueous solution of the molal KI is diluted with water, concentration decreases , therefore the vapour pressure of the resulting solution increases.

40.Ans: (c)
If compound dissociates in solvent i>1, and on association i< 1.

50 (b) The relation, ΔT_b = k_b.m hold good only when solute is non-volatile. Toluene and ethanol are volatile solvents. Thus, choices (Boiling point of pure water decreases by the addition of ethanol) and (Boiling point of pure benzene increases by the addition of toluene) are wrong. Further, for a solute to show colligative effect in a solution, the solution should obey Raoult- law. A solution of HNO₃ , in water shows negative deviation from Raoult- law. Thus, the only correct choice is (Vapour pressure of pure benzene decreases by the addition of naphthalene)